only you know how he works and how your parents will take this news...my approach would be to be straight forward with both of them...he's going to freak out as you said because it wasnt a serious relationship but he took that chance by not protecting himself
your parents may act shocked but hopefull will become more supportive over time...
best of luck to you
Okay...well first off...if it's not all that serious between the two of you, how do you think he will be as a father? Do you think that after the initial "OMG" he will be around and help with the pregnancy and the baby after it's born? If not...I wouldn't ease him into it..I would just be like "Hey I'm pregnant"
And honestly...there really isn't any other way to tell someone. I'm pregnant, I'm knocked up...whatever, You can be nice about it, and not judge is he looses his lunch or doesn't call for a few days.
As far as your parents go..."Mom I'm Pregnant" works pretty well.
There really is no way to say it...You can keep an open mind about the reactions people might have, and not be upset when they don't jump up and down with tears of joy running down their faces. I'm sure this is difficult for you right now, but you have to realize your not the only one in this anymore, so negative reactions at first should be accepted. I'm sure they will come around to the fact later on, but i'm sure it's going to be a shocker for all.
Good luck!
For your parents, it might be hard because of course it's going to be a shock. (It also depends on your age as well) If you're still living with them it's likely they're going to have to help support you. They might be upset, mad, and/or disappointed. Be mature about it when you tell them. You made the choice of having sex, and now have to face those consequences, both positive and negative.